/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | foam-extend: Open Source CFD
   \\    /   O peration     | Version:     4.1
    \\  /    A nd           | Web:         http://www.foam-extend.org
     \\/     M anipulation  | For copyright notice see file Copyright
-------------------------------------------------------------------------------
License
	This file is part of foam-extend.

	foam-extend is free software: you can redistribute it and/or modify it
	under the terms of the GNU General Public License as published by the
	Free Software Foundation, either version 3 of the License, or (at your
	option) any later version.

	foam-extend is distributed in the hope that it will be useful, but
	WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
	General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with foam-extend.  If not, see <http://www.gnu.org/licenses/>.

Class
	Foam::fileMonitor

Description
	Checking for changes to files.

Note
	The default is to use stat to get the timestamp.

	Compile with FOAM_USE_INOTIFY to use the inotify
	(Linux specific, since 2.6.13) framework. The problem is that inotify does
	not work on nfs3 mounted directories!!

SourceFiles
	fileMonitor.C

\*---------------------------------------------------------------------------*/

#ifndef fileMonitor_H
#define fileMonitor_H

#include <sys/types.h>
#include "NamedEnum.H"
#include "className.H"
#include "DynamicList.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

class fileMonitor;
class fileMonitorWatcher;


class fileMonitor
{

public:

	// Public data types

		//- Enumeration defining the file state.
		enum fileState
		{
			UNMODIFIED = 0,
			MODIFIED = 1,
			DELETED = 2
		};

		static const NamedEnum<fileState, 3> fileStateNames_;

private:
	// Private data

		//- Whether to use inotify (requires -DFOAM_USE_INOTIFY, see above)
		const bool useInotify_;

		//- State for all watchFds based on local files
		mutable DynamicList<fileState> localState_;

		//- State for all watchFds - synchronised
		mutable DynamicList<fileState> state_;

		//- Filename for all watchFds
		DynamicList<fileName> watchFile_;

		//- Free watchFds
		DynamicList<label> freeWatchFds_;

		//- Watch mechanism (stat or inotify)
		mutable autoPtr<fileMonitorWatcher> watcher_;


	// Private Member Functions

		//- Update localState_ from any events.
		void checkFiles() const;

		//- Disallow default bitwise copy construct
		fileMonitor(const fileMonitor&);

		//- Disallow default bitwise assignment
		void operator=(const fileMonitor&);


public:

	// Declare name of the class and its debug switch
	ClassName("fileMonitor");

	// Constructors

		//- Construct null
		fileMonitor(const bool useInotify);


	//- Destructor
	~fileMonitor();


	// Member Functions

		//- Add file to watch. Return watch descriptor
		label addWatch(const fileName&);

		//- Remove file to watch. Return true if successful
		bool removeWatch(const label watchFd);

		//- Get name of file being watched
		const fileName& getFile(const label watchFd) const;

		//- Check state using handle
		fileState getState(const label watchFd) const;

		//- Check state of all files. Updates state_.
		void updateStates
		(
			const bool masterOnly,
			const bool syncPar
		) const;

		//- Reset state (e.g. after having read it) using handle
		void setUnmodified(const label watchFd);
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //
